Since completing the UAV & power mods on my 5200, I have noticed that the 5200's video output is very jumpy on my Vizio D43fx-F4 TV. I took a slow-motion-video that demonstrates the problem.
I have learned that Vizio TVs often have trouble with the composite output produced by the UAV, so as part of my troubleshooting process, I connected my 5200 to my other TV, a Sharp LC-52D64U. The 5200's composite signal to the Sharp is solid and strong, so now we have determined that the problem is the TV.
I ordered an OREI composite/S-video to HDMI converter which should arrive tomorrow. Reports from other AtariAge users are that this unit works well; I'll see.
My 2600 also has jumpy video, but it's not a fast jump like 5200: where the 5200's issue just looks like a fuzzy screen (because it is basically a fast-motion, 1-pixel up-and-down jump), the 2600's issue is that it seems to lose sync, and the image is scrolled about 1/4 to 1/3 of the way up. Even so, I wonder if the TV is the problem with the 2600, and if the converter box will fix it. I'm guessing that if it works for the 5200, it will also solve the 2600's problem. I hope so -- it would be nice to have both of these issues fixed.